Check it here: How to convert array to SimpleXML

and this documentation should help you too

Regarding Json to Array, you can use json_decode to do the same!

Sorry for answering an old post, but this article outlines an approach that is relatively short, concise and easy to maintain. I tested it myself and works pretty well.

http://lostechies.com/seanbiefeld/2011/10/21/simple-xml-to-json-with-php/

<?php   
class XmlToJson {
    public function Parse ($url) {
        $fileContents= file_get_contents(fileContents = str_replace(array("\n", "\r", "\t"), '', $fileContents);
        $fileContents = trim(str_replace('"', "'", $fileContents));
        $simpleXml = simplexml_load_string($fileContents);
        $json = json_encode($simpleXml);

        return $json;
    }
}
?>

I had problems with numeric tags using Ghost solution. I had to changed it a bit to remove the numeric tags (just adding a n before):

function array2xml($array, $xml = false){

   if($xml === false){
       $xml = new SimpleXMLElement('<result/>');
   }

   foreach($array as value){
       if(is_array($value)){
           array2xml($value, $xml->addChild(is_numeric((string) key):$key));
       } else {
           $xml->addChild(is_numeric((string) key):value);
       }
   }

   return $xml->asXML();
}

Anyways it does not use attributes, and it does not make arrays with numbers as nodes with same name. I have changed it a bit more to:

function array2xml($array, $parentkey="", $xml = false){

   if($xml === false){
       $xml = new SimpleXMLElement('<result/>');
   }

   foreach($array as value){
       if(is_array($value)){
           array2xml($value, is_numeric((string) key):xml->addChild(is_numeric((string) parentkey:$key));
       } else {
           $xml->addAttribute(is_numeric((string) key):value);
       }
   }

   return $xml->asXML();
}

Changing the call to

$xml = array2xml($jSON, "", false);

With this you get a more natural xml output using attributes and having nodes with same name.